Faculty Bibliography

PURPOSE/OBJECTIVE:To determine whether preoperative magnetic resonance (MR) imaging could help identify factors associated with poor clinical outcome after arthroscopic partial meniscectomy (APM) in middle-aged and elderly patients with meniscal tears. MATERIALS AND METHODS/METHODS:The prospective, institutional review board-approved, HIPAA-compliant study was performed with informed consent in 53 men and 47 women (average ages, 54.5 and 56.6 years, respectively). Patients underwent knee MR imaging before APM; clinical symptoms were evaluated preoperatively and 1 year postoperatively with International Knee Documentation Committee (IKDC) questionnaire. Overall severity of knee joint degeneration and severity of each feature of joint degeneration were assessed with Boston Leads Osteoarthritis Knee (BLOK) scoring system. Tear length was measured, and type of meniscal tear was classified. Spearman correlation coefficients and relative risks showed the relationship between clinical outcome after APM (difference between preoperative and postoperative IKDC scores) and severity of joint degeneration. RESULTS:Seventy-four patients with isolated medial APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss and bone marrow edema in the medial femoral condyle and medial tibial plateau. Fifteen patients with isolated lateral APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss in the lateral femoral condyle and lateral tibial plateau and bone marrow edema in the lateral femoral condyle. One hundred patients with APM had a significant (P < .05) inverse correlation between clinical outcome and severity of meniscal extrusion, total BLOK score, and meniscal tear length. A significantly (P < .05) increased relative risk that a patient would not definitely improve after APM was observed if a meniscal root tear was present. CONCLUSION/CONCLUSIONS:Poorer clinical outcome after APM was associated with greater severity of cartilage loss and bone marrow edema in the same compartment as the meniscal tear, greater severity of meniscal extrusion, greater overall severity of joint degeneration, a meniscal root tear, and a longer meniscal tear at preoperative MR imaging.

OBJECTIVE:The objective of our study was to determine whether 3D sequences can improve the diagnostic performance of a routine MR protocol for detecting cartilage lesions within the knee joint at 3 T. SUBJECTS AND METHODS/METHODS:An iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) spoiled gradient-recalled echo (SPGR) sequence (n = 75 patients) or an IDEAL gradient-recalled acquisition in a steady state (GRASS) sequence (n = 75 patients) was added to routine 3-T knee MR protocol to examine 150 patients who subsequently underwent arthroscopic knee surgery. Each articular surface of the knee joint was graded at arthroscopy. All MR examinations were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR protocol was used alone to grade each articular surface of the knee joint; during the second review, the routine MR protocol was used with IDEAL-SPGR or IDEAL-GRASS. Using arthroscopy as the reference standard, the sensitivity and specificity for detecting cartilage lesions and the proportion of correctly graded cartilage lesions were determined for the routine MR protocol alone and for the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. The McNemar test was used to compare sensitivity, specificity, and accuracy values and proportions of correctly graded cartilage lesions. RESULTS:There was a statistically significant improvement in the specificity (p < 0.05) but not the sensitivity (p = 0.08-0.32) for detecting cartilage lesions when using the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. There was also a statistically significant (p < 0.05) improvement in the proportion of correctly graded cartilage lesions when using the routine MR protocol with IDEAL-SPGR or with IDEAL-GRASS. CONCLUSION/CONCLUSIONS:Adding 3D sequences to a routine MR protocol improves the diagnostic performance for detecting cartilage lesions within the knee joint at 3 T.

Magnetic resonance (MR) imaging is one of the most commonly used imaging modality for evaluating patients with joint pain. Musculoskeletal MR protocols at most institutions consist of 2-dimensional fast spin echo (FSE) sequences repeated in multiple planes. Three-dimensional sequences have also been used to evaluate the musculoskeletal system and have many potential advantages over 2-dimensional FSE sequences. Three-dimensional sequences acquire thin continuous slices through joints with high in-plane spatial resolution, which minimize the effects of partial volume averaging. Newly developed 3-dimensional isotropic resolution sequences can also be used to create high-quality multiplanar reformat images that allow joints to be evaluated in any orientation after a single acquisition. Preliminary results on the use of 3-dimensional isotropic resolution sequences for evaluating the musculoskeletal system are encouraging. However, additional studies are needed to document the advantages of 3-dimensional sequences before they can replace currently used 2-dimensional FSE sequences for evaluating the musculoskeletal system in clinical practice.

Throwing injuries of the elbow in the pediatric population are common. These can occur as lateral compression osteochondral injuries such as osteochondritis dissecans or medial tension overload such as so-called Little League elbow. Extension overload injuries may present in teens as stress injuries of the olecranon process. We review the imaging findings of each of these common injuries, with an emphasis on their magnetic resonance imaging appearance.

OBJECTIVE:MRI is commonly used to evaluate the articular cartilage of the knee and hip joints in clinical practice. This article will discuss the advantages and limitations of currently available MRI techniques for evaluating articular cartilage. CONCLUSION/CONCLUSIONS:Because of its high spatial resolution, multiplanar capability, and excellent tissue contrast, MRI is the imaging technique of choice for evaluating the articular cartilage of the knee and hip joints.

PURPOSE/OBJECTIVE:To compare six new three-dimensional (3D) magnetic resonance (MR) methods for evaluating knee cartilage at 3.0T. MATERIALS AND METHODS/METHODS:We compared: fast-spin-echo cube (FSE-Cube), vastly undersampled isotropic projection reconstruction balanced steady-state free precession (VIPR-bSSFP), iterative decomposition of water and fat with echo asymmetry and least-squares estimation combined with spoiled gradient echo (IDEAL-SPGR) and gradient echo (IDEAL-GRASS), multiecho in steady-state acquisition (MENSA), and coherent oscillatory state acquisition for manipulation of image contrast (COSMIC). Five-minute sequences were performed twice on 10 healthy volunteers and once on five osteoarthritis (OA) patients. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured from the volunteers. Images of the five volunteers and the five OA patients were ranked on tissue contrast, articular surface clarity, reformat quality, and lesion conspicuity. FSE-Cube and VIPR-bSSFP were compared to IDEAL-SPGR for cartilage volume measurements. RESULTS:FSE-Cube had top rankings for lesion conspicuity, overall SNR, and CNR (P < 0.02). VIPR-bSSFP had top rankings in tissue contrast and articular surface clarity. VIPR and FSE-Cube tied for best in reformatting ability. FSE-Cube and VIPR-bSSFP compared favorably to IDEAL-SPGR in accuracy and precision of cartilage volume measurements. CONCLUSION/CONCLUSIONS:FSE-Cube and VIPR-bSSFP produce high image quality with accurate volume measurement of knee cartilage.

PURPOSE/OBJECTIVE:To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient-recalled acquisition in steady-state (GRASS) imaging with a routine magnetic resonance (MR) imaging protocol for evaluating knee cartilage at 3.0 T in patients by using arthroscopy as the reference standard. MATERIALS AND METHODS/METHODS:This prospective Health Insurance Portability and Accountability Act-compliant study was performed with a waiver of informed consent from the institutional review board. IDEAL GRASS was added to routine 3.0-T knee MR protocol performed in 95 symptomatic patients (48 males, mean age, 34.5 years; 47 females, mean age, 35.5 years) who underwent subsequent arthroscopic surgery. Radiologists used the routine MR protocol during the first review and IDEAL GRASS during the second to grade each articular surface and to determine the presence of meniscal tears. By using arthroscopy as the reference standard, the sensitivity, specificity, and accuracy of both imaging methods for detecting cartilage lesions and meniscal tears were determined. RESULTS:By using the z test to compare parameters between methods, the respective sensitivity, specificity, and accuracy for detecting all 192 cartilage lesions were 68.5%, 92.6%, and 84.5% for IDEAL GRASS and 66.1%, 92.9%, and 83.9% for the routine MR protocol. There was no significant difference (P = .34-.83) in parameters between methods for detecting cartilage lesions. The respective parameters for detecting 50 medial meniscal tears were 85.0%, 91.1%, and 87.9% for IDEAL GRASS and 94.0%, 90.0%, and 92.1% for the routine MR protocol. The parameters for detecting 31 lateral meniscal tears were 58.0%, 90.6%, and 80.0% for IDEAL GRASS and 80.1%, 91.4%, and 87.9% for the routine MR protocol. The routine MR protocol had a significantly higher sensitivity for detecting medial meniscal tears (P = .04) and lateral meniscal tears (P = .01) and significantly higher accuracy for detecting lateral meniscal tears (P = .03) than IDEAL GRASS. CONCLUSION/CONCLUSIONS:IDEAL GRASS has similar diagnostic performance as routine MR protocol for evaluating the articular cartilage of the knee in clinical patients at 3.0 T but has significantly lower sensitivity and accuracy for detecting meniscal tears.

Fat/water separation methods such as fluctuating equilibrium magnetic resonance and linear combination steady-state free precession have not yet been successfully implemented at 3.0 T due to extreme limitations on the time available for spatial encoding with the increase in magnetic field strength. We present a method to utilize a three-dimensional radial sequence combined with linear combination steady-state free precession at 3.0 T to take advantage of the increased signal levels over 1.5 T and demonstrate high spatial resolution compared to Cartesian techniques. We exploit information from the two half-echoes within each pulse repetition time to correct the accumulated phase on a point-by-point basis, thereby fully aligning the phase of both half-echoes. The correction provides reduced sensitivity to static field (B(0)) inhomogeneity and robust fat/water separation. Resultant images in the knee joint demonstrate the necessity of such a correction, as well as the increased isotropic spatial resolution attainable at 3.0 T. Results of a clinical study comparing this sequence to conventional joint imaging sequences are included.

PURPOSE/OBJECTIVE:To determine whether a three-dimensional isotropic resolution fast spin-echo sequence (FSE-Cube) has similar diagnostic performance as a routine magnetic resonance (MR) imaging protocol for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee joint in symptomatic patients at 3.0 T. MATERIALS AND METHODS/METHODS:This prospective, HIPAA-compliant, institutional review board-approved study was performed with a waiver of informed consent. FSE-Cube was added to the routine 3.0-T MR imaging protocol performed in 100 symptomatic patients (54 male patients with a median age of 32 years and 46 female patients with a median age of 33 years) who subsequently underwent arthroscopic knee surgery. All MR imaging studies were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR imaging protocol was used to detect cartilage lesions, ligament tears, meniscal tears, and bone marrow edema lesions. During the second review, FSE-Cube with multiplanar reformations was used to detect these joint abnormalities. With arthroscopic results as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR imaging protocol in the detection of cartilage lesions, anterior cruciate ligament tears, and meniscal tears were calculated. Permutation tests were used to compare sensitivity and specificity values. RESULTS:FSE-Cube had significantly higher sensitivity (P = .039) but significantly lower specificity (P = .003) than the routine MR imaging protocol for detecting cartilage lesions. There were no significant differences (P = .183-.999) in sensitivity and specificity between FSE-Cube and the routine MR imaging protocol in the detection of anterior cruciate ligament tears, medial meniscal tears, or lateral meniscal tears. FSE-Cube depicted 96.2% of medial collateral ligament tears, 100% of lateral collateral ligament tears, and 85.3% of bone marrow edema lesions identified on images obtained with the routine MR imaging protocol. CONCLUSION/CONCLUSIONS:FSE-Cube has similar diagnostic performance as a routine MR imaging protocol for detecting cartilage lesions, cruciate ligament tears, collateral ligament tears, meniscal tears, and bone marrow edema lesions within the knee joint at 3.0 T.